High-intensity ultrasound together with heat treatment improves the oil-in-water emulsion stability of egg white protein peptides

Effect of ultra-high pressure combined with heat-assisted treatment on the characterization, moisture absorption, and antioxidant activity properties of walnut peptide

In this study, ultra-high pressure (UHP) and heat-assisted technology (HT) were used to process walnut peptides (WP) and investigate their combined effects (UHP-HT) on the characterization, moisture absorption, and antioxidant activity of WP. The results indicated that UHP (300 Mpa, 10 min) combined with HT treatment (55 °C, 30 min) significantly increased the surface hydrophobicity and disulfide bonds of WP. UHP-HT-treated WP exhibited lower moisture absorption and more stable water molecule migration. Additionally, the moisture absorption capacity of the WP (48.78 %) was significantly decreased in WP-UHP, WP-HT and WP-UHP (45.37 %, 43.15 %, and 40.19 %, respectively) because of increasing the surface hydrophobicity. UHP-HT combined improved structural characteristics, including particle size, zeta potential, and functional group stability, and significantly enhanced the antioxidant activity of WP under high humidity conditions. Overall, these findings suggest that UHP-HT can effectively reduce the moisture absorption of WP, thus enhancing its storage stability and extending its shelf life.

Characterization of the effects of insoluble soybean polysaccharides on the formation and physicochemical properties of soybean isolate protein gel

The effects of insoluble soybean polysaccharides (ISPS) on the formation and physicochemical properties of soybean protein isolate (SPI) gel were studied. As ISPS concentration increased, SPI suspensions showed reduced surface hydrophobicity and zeta-potential and enhanced thermal stability. However, the zeta-potential increased after gel formation. The ISPS decreased the hardness of the 6 % SPI gel, which could be attributed to the fact that ISPS reduced the elasticity of gel network, making the microstructure loose and porous and behaving as a weak gel; however, for the 10 % SPI gel, the ISPS promoted the increase in hardness and exhibited a weaker negative impact on the textural and microstructural properties of SPI gel. Results revealed that ISPS could react with SPI via non-covalent bonds and embedded into the protein network, weakening or strengthening the structure and texture of SPI gel and this impact is related to the mass ratio between these two biopolymers.

Studies on the Efficient Extraction of Ovotransferrin and the Effect of Heating Treatment on Its Structure and Activity

Ovotransferrin (OVT) is very rich in nutritional value and possesses a variety of biological activities. However, there is a lack of suitable OVT extraction methods that are simple and suitable for large-scale production. For this reason, this study explored a new method of ovalbumin OVT extraction based on mesophilic treatment. The effects of different heat treatment conditions on the physicochemical properties and bioactivities of the prepared OVT and their influence mechanisms were investigated. The results showed that OVT could be efficiently extracted from egg white by moderate heat treatment. Based on single factor experiments, response surface methodology was used to determine the effects of heat treatment time, temperature and pH on the extraction rate of OVT. The yield was 93.65 ± 0.53% under the optimal extraction conditions (62.5 °C, 75 min, pH 8). SDS-PAGE and FT-IR showed that changes in the influencing factors during heating had different effects on OVT. In addition, different extraction parameters had different effects on the iron-binding and antioxidant capacities of OVT. This study provides a fast and efficient preparation method for OVT from egg white, which lays the foundation for the wide application of OVT.

Egg white protein under thermal stress: Thermal aggregation orientation and gel properties decline

This study investigates the effects of varying heat stress temperatures (56 °C to 76 °C) on the gel characteristics of egg white protein. The results indicate that when the heat stress temperature exceeds 60 °C, the textural properties, water-holding capacity, and freeze-thaw stability of egg white gel (EWG) decrease to varying extents compared to untreated EWG. At 76 °C, the proportion of free water in EWG increases from 0.9 % to 1.4 %, while rigidity, as observed in rheological analysis, decreases by approximately 48.6 %. Additionally, the α-helix content in the secondary structure reduces by approximately 20.1 %, and notable changes occur in the crystalline structure, with decreased peak intensities in Ultraviolet and both intrinsic and extrinsic fluorescence spectra. Furthermore, weakened intermolecular interactions in EWG result in the formation of larger aggregates within the microstructure. These findings suggest that increased heat stress promotes protein aggregation into disordered clusters, forming a porous gel network that releases water under external forces. This explains the observed decline in texture and water-holding capacity. The study provides a theoretical basis for improving the production and processing of egg white protein products and developing future strategies to mitigate protein aggregation.

Role of Medium-Chain Triglycerides on the Emulsifying Properties and Interfacial Adsorption Characteristics of Pork Myofibrillar Protein

Medium-chain triglycerides (MCTs) have been known to have multiple health benefits in treating metabolic disorders and reducing the incidence of obesity. In the present study, the partial replacement of lard with MCTs assisted by ultrasound treatment on the emulsifying stability and adsorption behavior of myofibrillar protein (MP) was investigated. The results revealed that ultrasound-assisted MCT emulsion had better emulsifying activity and emulsion stability than other groups. MCTs with ultrasound treatment considerably lowered the particle size, facilitated the formation of much smaller and more homogeneous emulsion droplets, and enhanced the oxidative stability of the emulsion. The emulsion had a pseudo-plastic behavior determined through static and dynamic rheological studies, and the MCT emulsion exhibited a larger viscosity and a greater storage modulus (G') compared with the lard emulsion. MCTs could promote protein adsorption levels at the O/W interface, forming a dense interfacial protein film. The surface hydrophobicity and reactive sulfhydryl content increased, accompanied by the transformation of α-helix and β-turn structure to β-sheet and random coil structure, indicating MCTs combined with ultrasound-induced unfolding and crosslinking of MP at the interface. The results suggested that MCTs may have the potential to enhance emulsifying properties in emulsion-type meat products.

Unveiling the regulatory mechanism of pulsed electric field modified instant soy milk powder: Exploring allergenicity, conformation, and epitopes

Glycinin and β-conglycinin are prominent allergens, limiting the safety of soy and soy products in a wide range of applications. The study investigated the effects of pulsed electric field (PEF) on allergenicity, conformation, and epitopes of instant soy milk powder (ISMP) and the simulated digestion products (SDP), and to preliminarily elucidate the regulatory mechanism using multispectroscopy and peptidomics. The allergenicity of SDP and ISMP treated at 20 and 30 kV/cm were reduced and conformations were altered, especially decrease or disappearance of α-helix, enhancement of random coil, and reduction of hydrogen and disulfide bonds in SDP (P < 0.05). Furthermore, their digestion-resistant linear epitopes (DRLE) were differed, such as RSQSDN, EEEEQRQQ, and SRNPIY, therein N and P might be critical amino acids affecting their allergenicity. Overall, PEF reduced the ISPM allergenicity by altering conformations, increasing sensitivities to gastrointestinal digestive enzymes, and modulating binding sites to IgE by covering or disrupting linear epitopes.

Impact of ultrasonic pretreatment on pumpkin seed protein: Effect on protease activities, protein structure, hydrolysis kinetics and functional properties

Adding value to food by-products, such as pumpkin seeds, is an important strategy for the complete utilization of plant foods and advancing sustainability goals. This study aimed to maximize the production of bioactive peptides from pumpkin seed protein (PSP) by combining ultrasonic (US) pretreatment (40 kHz, 23.8 W/L) with enzymatic hydrolysis. The PSP's structure after sonication and its effects on the commercial proteases (Brauzyn®, Flavourzyme®, Neutrase®) activity and degree of hydrolysis were studied. The hydrolysis consequences regarding solubility and antioxidant activity of the resulting peptides were also evaluated. Sonication of PSP increased enzymatic activity by up to 21.3 % for Brauzyn®, 24.8 % for Flavourzyme® and 19.2 % for Neutrase®. Consequently, there was an increase in the degree of hydrolysis (up to 89 %) using sonicated PSP, particularly at 60 min/40 °C. These effects can be attributed to ultrasound-induced protein conformation changes, including increased intrinsic fluorescence intensity (<22 %), shifts in UV spectra, and alterations in FTIR amide bands, especially a decrease in β-sheet content (<7.14 %). Additionally, ultrasonic pretreatment reduced particle size (<43.9 %) and polydispersity index (<58 %), enhancing enzyme accessibility by fragmenting protein aggregates, as observed via scanning electron microscopy. As a result, the peptides obtained from the hydrolysis of sonicated PSP exhibited higher protein solubility (12 % to 49 % at pH 6.0) and improved antioxidant activity (5.6 % to 77 %). Overall, sonication of PSP for 60 min at 40 °C followed by hydrolysis with Neutrase® proved to be the most effective strategy for producing highly soluble peptides with enhanced antioxidant properties, highlighting the potential of ultrasound as a valuable tool for optimizing bioactive peptide production. Based on these results, the developed process is ready for scale-up by the food industry, aiming to obtain protein hydrolysates with improved functional and/or nutritional properties from a low-cost raw material. In parallel, further researches can focus on the potential application of these hydrolysates as ingredients in bakery, meet or dairy products.

Gum arabic-stabilized emulsion systems: Underlying mechanisms for enhancing storage and digestion stability of curcumin

Although the benefits of gum arabic (GA) in developing emulsion systems are well known, the mechanism underlying its stability-enhancing effect of GA in emulsion systems stabilized with curcumin remains unclear. This study used GA-stabilized emulsion system, containing 10 wt% medium-chain triglycerides and 0.1 % curcumin. Results demonstrated that when the GA concentration exceeded 0.5 wt%, the interface layer reached saturation, maintaining a consistent thickness of approximately 34.8 nm. The curcumin-containing emulsion demonstrated good stability during storage at room temperature and heating treatment, effectively protecting the curcumin. However, during in vitro intestinal digestion, the formation of salt and protein bridges caused the aggregation of oil droplets, resulting in an increase in the droplet size to 975.2 nm, while the curcumin content remained stable. Additionally, the in vitro release rate of encapsulated curcumin (44.0 %) was significantly higher than that of free curcumin (19.5 %). In conclusion, this study elucidated the stability-enhancing mechanism of GA-stabilized emulsions for curcumin and highlighted the potential of GA in developing emulsion systems for the encapsulation of these compounds.

Investigating the impact of ultrasound on the structural, physicochemical, and emulsifying characteristics of Dioscorin: Insights from experimental data and molecular dynamics simulation

This study investigated the impact of ultrasound treatment on dioscorin, the primary storage protein found in yam tubers. Three key factors, namely ultrasound power, duration, and frequency, were focused on. The research revealed that ultrasound-induced cavitation effects disrupted non-covalent bonds, resulting in a reduction in α-helix and β-sheet contents, decreased thermal stability, and a decrease in the apparent hydrodynamic diameter (Dh) of dioscorin. Additionally, previously hidden amino acid groups within the molecule became exposed on its surface, resulting in increased surface hydrophobicity (Ho) and zeta-potential. Under specific ultrasound conditions (200 W, 25 kHz, 30 min), Dh decreased while Ho increased, facilitating the adsorption of dioscorin molecules onto the oil-water interface. Molecular dynamics (MD) simulations showed that at lower frequencies and pressures, the structural flexibility of dioscorin's main chain atoms increased, leading to more significant fluctuations between amino acid residues. This transformation improved dioscorin's emulsifying properties and its oil-water interface affinity.

Emulsifying properties of egg proteins: Influencing factors, modification techniques, and applications

As an essential food ingredient with good nutritional and functional properties and health benefits, eggs are widely utilized in food formulations. In particular, egg proteins have good emulsification properties and can be commonly used in various food products, such as mayonnaise and baked goods. Egg protein particles can act as stabilizers for Pickering emulsions because they can effectively adsorb at the oil-water interface, reduce interfacial tension, and form a stable physical barrier. Due to their emulsifying properties, biocompatibility, controlled release capabilities, and ability to protect bioactive substances, egg proteins have become ideal carriers for encapsulating and delivering functional substances. The focus of this review is to summarize current advances in using egg proteins as emulsifiers. The effects of influencing factors (temperature, pH, and ionic strength) and various modification methods (physical, chemical, and biological modification) on the emulsifying properties of egg proteins are discussed. In addition, the application of egg proteins as emulsifiers in food products is presented. Through in-depth research on the emulsifying properties of egg proteins, the optimization of their applications in food, biomedical, and other fields can be achieved.

Study on the gelling properties of egg white/surfactant system by different heating intensities

The aim of this study was to elucidate the different effects and difference mechanism of gelling properties among egg white (EW) treated with different heating intensities and the composite addition of rhamnolipid and soybean lecithin. Particle size analyzer, potentiometric analyzer, surface hydrophobicity method, and Fourier transform infrared spectroscopy techniques were used to determine the physicochemical properties and molecular structure, respectively. Low-field nuclear magnetic resonance, magnetic resonance imaging, texture profile analysis, and scanning electron microscopy techniques were used to analyze the gelling properties and gel structure, respectively. And we illuminate the different mechanisms in the gelling properties of the EW with various treatments and key internal factors that play important roles in improving gelling properties by establishing the link between the gelling properties and relevant characteristics by mixed effects model and visual network analysis. The results indicate raising the content of rhamnolipid decreased the migration of immobilized water in the EW gel and the free water content. At the heating intensities of 55 °C/3.5, 65 °C/2.5, and 67 °C/1.5 min, with an increase in rhamnolipid, the gel's cohesiveness, gumminess, and chewiness gradually increased. The mixed effects model indicated that heating intensities and composite ratios have a 2-way interaction on zeta potential, the relaxation time of bound water (T21), the content of bound water (P21), the content of immobilized water (P22), and fractal dimension (df) attributes (P < 0.05). The visual network analysis showed that the protein solubility, the relaxation time of immobilized water (T22), surface hydrophobicity, zeta potential, average particle size (d43) and the relaxation time of free water (T23) are critical contributors to the different gelling properties of EW subjected to various treatments and the improvement of gelling properties. This study will provide theoretical guidance for the development of egg white products and the expansion of egg white's application scope in the egg product processing industry.

Oleanolic acid nanoparticles-stabilized W/O Pickering emulsions: Fabrication, characterization, and delivery application

Water-in-oil (W/O) Pickering emulsions have wide applications in the food industries. However, the existing W/O Pickering particles have disadvantages such as lack of bioactivity and poor stability. In this study, naturally occurring bioactive oleanolic acid (OA) was used as a novel emulsifier for W/O emulsions. Results revealed that rod-like OA could formulate into spherical nanoparticles by self-assembly, and then be anchored onto the oil-water interface to stabilize the emulsions. Besides, both OA concentration and internal water fraction (φ) had significant effect on the properties of emulsions. Furthermore, the resulted emulsions exhibited potential application as carriers for epigallocatechin-3-gallate (EGCG), which significantly improved its UV and thermal stability. Meanwhile, it could effectively protect EGCG from gastric digestion, and controlled release in the intestine. This work demonstrated the successful application of OA as a stabilizer for W/O emulsions, and provided valuable insight into its potential as delivery system for hydrophilic instable compounds.

Effects of ultrasound and thermal treatment on the interaction between hyaluronic acid and lactoferrin: Preparation, structures and functionalities

Complexes of polysaccharides and proteins have superior physicochemical and functional properties compared to single proteins or polysaccharides. In this study, lactoferrin-hyaluronic acid (LF-HA) complexes were prepared by both ultrasonic and thermal treatment. Appropriate preparation conditions, including ultrasonic and thermal treatment conditions, have been established. The complexes formed by different methods were structurally characterized by sodium dodecyl sulfate polyacrylamide gel electrophoresis, fourier transform infrared spectroscopy, and circular dichroism spectroscopy. Ultrasound formed non-covalent binding, while thermal treatment generated covalent bonding, altering the structure of LF. The LF-HA complexes showed improved heat stability, foaming stability, emulsifying activity and antioxidant capacity, but deceased foaming ability. Iron binding ability could only be improved by HA through thermal treatment. Moreover, the in vitro digestibility of LF-HA complexes decreased to below 80 % compared to LF.

Exploring the binding mechanisms of thermally and ultrasonically induced molten globule-like β-lactoglobulin with heptanal as revealed by multi-spectroscopic techniques and molecular simulation

This work employed the model protein β-lactoglobulin (BLG) to investigate the contribution of microstructural changes to regulating the interaction patterns between protein and flavor compounds through employing computer simulation and multi-spectroscopic techniques. The formation of molten globule (MG) state-like protein during the conformational evolution of BLG, in response to ultrasonic (UC) and heat (HT) treatments, was revealed through multi-spectroscopic characterization. Differential MG structures were distinguished by variations in surface hydrophobicity and the microenvironment of tryptophan residues. Fluorescence quenching measurements indicated that the formation of MG enhanced the binding affinity of heptanal to protein. LC-MS/MS and NMR revealed the covalent bonding between heptanal and BLG formed by Michael addition and Schiff-base reactions, and MG-like BLG exhibited fewer chemical shift residues. Molecular docking and molecular dynamics simulation confirmed the synergistic involvement of hydrophobic interactions and hydrogen bonds in shaping BLG-heptanal complexes thus promoting the stability of BLG structures. These findings indicated that the production of BLG-heptanal complexes was driven synergistically by non-covalent and covalent bonds, and their interaction processes were influenced by processes-induced formation of MG potentially tuning the release and retention behaviors of flavor compounds.

Study on stabilized mechanism of high internal phase Pickering emulsions based on commercial yeast proteins: Modulating the characteristics of Pickering particle via sonication

The primary significance of this work is that the commercial yeast proteins particles were successfully used to characterize the high internal phase Pickering emulsions (HIPPEs). The different sonication time (0,3,7,11,15 min) was used to modulate the structure and interface characteristics of yeast proteins (YPs) that as Pickering particles. Immediately afterward, the influence of YPs particles prepared at different sonication time on the rheological behavior and coalescence mechanism of HIPPEs was investigated. The results indicate that the YPs sonicated for 7 min exhibited a more relaxed molecular structures and conformation, the smallest particle size, the highest H0 and optimal amphiphilicity (the three-phase contact (θ) was 88.91°). The transition from extended to compact conformations of YPs occurred when the sonication time exceeded 7 min, resulting in an augmentation of size of YPs particles, a reduction in surface hydrophobicity (H0), and an elevation in hydrophilicity. The HIPPEs stabilized by YPs particles sonicated for 7 min exhibited the highest adsorption interface protein percentage and a more homogeneous three-dimensional (3D) protein network, resulting in the smallest droplet size and the highest storage (G'). The HIPPEs sample that stabilized by YPs particles sonicated for 15 min showed the lowest adsorption protein percentage. This caused a reduction in the thickness of its interface protein layer and an enlargement in the droplet diameter (D [3,2]). It was prone to droplet coalescence according to the equation used to evaluate the coalescence probability of droplets (Eq (2)). And the non-adsorbed YPs particles form larger aggregation structures in the continuous phase and act as "structural agents" in 3D protein network. Therefore, mechanistically, the interface protein layer formed by YPs particles sonicated 7 min contributed more to HIPPEs stability. Whereas the "structural agents" contributed more to HIPPEs stability when the sonication time exceeded 7 min. The present results shed important new light on the application of commercial YPs in the functional food fields, acting as an available and effective alternative protein.

Ultrasound-induced structural changes of different milk fat globule membrane protein-phospholipids complexes and their effects on physicochemical and functional properties of emulsions

Ultrasonic technology is a non-isothermal processing technology that can be used to modify the physicochemical properties of food ingredients. This study investigated the effects of ultrasonic time (5 min, 10 min, 15 min) and power (150 W,300 W,500 W) on the structural properties of three types of phospholipids composed of different fatty acids (milk fat globule membrane phospholipid (MPL), egg yolk lecithin (EYL), soybean lecithin (SL)) and milk fat globule membrane protein (MFGMP). We found that the ultrasound treatment changed the conformation of the protein, and the emulsions prepared by the pretreatment showed better emulsification and stability, the lipid droplets were also more evenly distributed. Meanwhile, the flocculation phenomenon of the lipid droplets was significantly improved compared with the non-ultrasonic emulsions. Compared with the three complexes, it was found that ultrasound had the most significant effect on the properties of MPL-MFGMP, and its emulsion state was the most stable. When the ultrasonic condition was 300 W, the particle size of the emulsion decreased significantly (from 441.50 ± 4.79 nm to 321.77 ± 9.91 nm) at 15 min, and the physical stability constants KE decreased from 14.49 ± 0.702 % to 9.4 ± 0.261 %. It can be seen that proper ultrasonic pretreatment can effectively improve the stability of the system. At the same time, the emulsification performance of the emulsion had also been significantly improved. While the accumulation phenomenon occurred when the ultrasonic power was 150 W and 500 W. These results showed that ultrasonic pretreatment had great potential to improve the properties of emulsions, and this study would provide a theoretical basis for the application of emulsifier in the emulsions.

Selenium Decipher: Trapping of Native Selenomethionine-Containing Peptides in Selenium-Enriched Milk and Unveiling the Deterioration after Ultrahigh-Temperature Treatment

Selenopeptide identification relies on databases to interpret the selenopeptide spectra. A common database search strategy is to set selenium as a variable modification instead of sulfur on peptides. However, this approach generally detects only a fraction of selenopeptides. An alternative approach, termed Selenium Decipher, is proposed in the present study. It involves identifying collision-induced dissociation-cleavable selenomethionine-containing peptides by iteratively matching the masses of seleno-amino acids in selenopeptide spectra. This approach uses variable-data-independent acquisition (vDIA) for peptide detection, providing a flexible and customizable window for secondary mass spectral fragmentation. The attention mechanism was used to capture global information on peptides and determine selenomethionine-containing peptide backbones. The core structure of selenium on selenomethionine-containing peptides generates a series of fragment ions, namely, C3H7Se+, C4H10NSe+, C5H7OSe+, C5H8NOSe+, and C7H11N2O2Se+, with known mass gaps during higher-energy collisional dissociation (HCD) fragmentation. De-selenium spectra are generated by removing selenium originating from selenium replacement and then reassigning the precursors to peptides. Selenium-enriched milk is obtained by feeding selenium-rich forage fed to cattle, which leads to the formation of native selenium through biotransformation. A novel antihypertensive selenopeptide Thr-Asp-Asp-Ile-SeMet-Cys-Val-Lys TDDI(Se)MCVK was identified from selenium-enriched milk. The selenopeptide (IC50 = 60.71 μM) is bound to four active residues of the angiotensin-converting enzyme (ACE) active pocket (Ala354, Tyr523, His353, and His513) and two active residues of zinc ligand (His387 and Glu411) and exerted a competitive inhibitory effect on the spatial blocking of active sites. The integration of vDIA and the iteratively matched seleno-amino acids was applied for Selenium Decipher, which provides high validity for selenomethionine-containing peptide identification.

Quantitative proteomics provides new insights into the mechanism of improving rehydration of egg white powder by ultrasonic pretreatment

Poor rehydration is one of the key factors affecting the functional properties of egg white powder (EWP). Reducing rehydrated precipitates is important for the processing and application of EWP. In this study, effects of ultrasonic pretreatment on the physicochemical and functional properties of EWP rehydration solutions were studied with the aim of revealing the mechanism of ultrasonic pretreatment to improve rehydration. Compared with freeze-dried EWP (FD) and spray-dried EWP (SD), the percentage of ultrasonic pretreated FD (UFD) and ultrasonic pretreated SD (USD) rehydrated precipitates decreased by 13.0 % and 5.6 %, respectively, after ultrasonic pretreatment (0.25 W/mL for 10 min); and the average particle sizes of UFD and USD solutions decreased by 22.5 % and 15.5 %, respectively. Fourier transform infrared spectroscopy showed that ultrasonic pretreatment caused higher β-sheet content in the protein secondary structure of UFD rehydrated precipitates (49.2 %). Quantitative proteomic analysis revealed a decrease in the abundance of major egg white proteins (ovalbumin, ovotransferrin, ovomucoid and ovomucin) in the rehydrated precipitates of UFD, except for lysozyme. It was also shown that lysozyme-centered aggregates were disrupted in the rehydrated precipitates of UFD. Our research suggests that ultrasonic pretreatment improves EWP rehydration by reducing the interactions between high abundance proteins as well as improving the solubility of high abundance proteins.

The influence of α and α' subunits on SPI Pickering emulsions based on natural hybrid breeding varieties

In this study, food-grade protein nanoparticles (Wild-NPs, α-lack-NPs, α'-lack-NPs, and (α + α')-lack-NPs) were organized as emulsion stabilizers via thermal induction. The effects of α and α' subunits in soybean protein isolate (SPI) on Wild nanoparticle Pickering emulsion (Wild-NPPEs), α-lack nanoparticle Pickering emulsion (α-lack-NPPEs), α'-lack nanoparticle Pickering emulsion (α'-lack-NPPEs) and (α + α')-lack nanoparticle Pickering emulsion ((α + α')-lack-NPPEs) were investigated. The Pickering emulsion stabilization mechanism indicated that the α'-lack-NPs particle size, surface hydrophobicity, and contact angle were mostly comparatively large. Therefore, the absence of the α' subunit made the desorption of protein nanoparticles at the oil and water interface require higher energy. Through the hydrophobic interaction between molecules, the structure and properties of the emulsion were improved, showing good stability. The existence of α'-lack-NPPEs leads to the formation of a gel-like network in the emulsion, which increases the viscosity of the emulsion and makes the network structure of the emulsion more uniform and denser.

Improvement of the emulsifying properties of Zanthoxylum seed protein by ultrasonic modification

The influence of ultrasonic treatment (100-500 W, 30 min) on the molecular structures and emulsifying properties of Zanthoxylum seed protein (ZSP) was explored for the first time in this work. Research results indicated that the all ultrasonic treatments at different power levels decreased the particle size but increased the surface charge of ZSP. In addition, the ultrasonic treatments induced the structural unfolding of the ZAP, as indicated by the increase in α-helix, ultraviolet-visible absorbance, surface hydrophobicity and the amount of surface free sulfhydryl groups, as well as the decrease in β-sheet and intrinsic fluorescence intensity. As a result, the significantly (p < 0.05) increased emulsifying activity index (EAI) and emulsion stability index (ESI) of ZSP were observed after ultrasonic treatment. In addition, the emulsion prepared by ultrasonically treated ZSP exhibited the smaller and more uniform droplets with significantly improved stability against environmental stress (temperature, salt concentration, pH), creaming and oxidation due to the increased ratio of interfacially adsorbed ZSP. Furthermore, ultrasonic treatment at 400 W was found to be the optimum condition for modification. These findings will provide a theoretical foundation for the utilization of ultrasound in enhancing the emulsifying properties of ZSP and promoting its application in the field of food processing.

High internal phase Pickering emulsions stabilised by ultrasound-induced soy protein-β-glucan-catechin complex nanoparticles to enhance the stability and bioaccessibility of curcumin

AIMS

To evaluate the potential applications of soy protein-glucan-catechin (SGC) complexes prepared with different ultrasound times in stabilising high internal phase Pickering emulsion (HIPPE) and delivering curcumin.

METHODS

The SGC complexes were characterised by particle size, morphology, zeta potential, Fourier transform infra-red, and fluorescence spectroscopy. Formation and stability of curcumin emulsions were monitored by droplet size, microstructure, rheological property, lipid oxidation, and in vitro digestion.

RESULTS

Short-time ultrasound-induced complexes (SGC-U15) exhibited a small size and wettability of ∼82.5°. The chemical stability and bioaccessibility of curcumin was greatly improved by SGC-U15-stabilised HIPPEs, even after 70 days of storage, heating at 100 °C for 30 min, ultraviolet irradiation for 120 min, and in vitro digestion, owing to the formation of elastic gel-like structure at the oil/water interfaces.

CONCLUSION

Our findings may contribute to the design of emulsion-based delivery systems using ultrasound-induced protein-polysaccharide-polyphenol complexes.

Polysaccharide-addition order regulates sonicated egg white peptide stabilized nanoemulsions and β-carotene digestion in vitro

In this paper, the effects of the polysaccharide-addition order (before and after homogenisation) on the stability of nanoemulsion stabilised by sonicated egg white peptides and the in vitro digestive behaviour of loaded β-carotene were investigated. The pyrene fluorescence results showed that the concentration of micelles formed by flaxseed gum (FG) in complex with peptides was significantly higher than that of peach gum (PG). The order of polysaccharide-addition affected the emulsion properties and stability; adding polysaccharides before homogenisation led to protein bridging flocculation, low polysaccharide coverage and a higher interfacial adsorbed protein content of the emulsion. PG enhanced potential spatial resistance and electrostatic repulsion, effectively prevented emulsion flocculation and improved electrostatic stability. After homogenisation, FG was added to emulsions to improve environmental stability, including ionic, temperature and storage stability. Due to the viscosity of polysaccharides and the formed polysaccharide-protein-lipid aggregates, the increasing degree of bridging flocculation promoted the prominent of apparent viscosity, and the G' and G'' exhibited a frequency-dependent increase. The polysaccharide type and mode changed the surface loading charge and droplet interface thickness, delayed the destruction of the droplet structure by protease, and slowed the release of β-carotene to form micelles. In this study, a stable emulsion system and an efficient emulsion transport system for bioactive substances were obtained by regulating polysaccharides adding order, which is significant for constructing an efficient food emulsion delivery system.

Preparation of high complex concentration emulsion stabilized by soy protein/dextran sulfate composite particles

BACKGROUND

Soy protein isolate (SPI) could be used as an emulsifier to stabilize emulsions, while SPI is unstable under low acidic conditions. The stable composite particles of SPI and dextran sulfate (DS) could be formed by the electrostatic interaction at the pH was 3.5. And the SPI/DS composite particles were used to prepare the high complex concentration emulsion. The stabilization properties of high complex concentration emulsion were investigated.

RESULTS

Compared to uncompounded SPI, the particle size of SPI/DS composite particles was smaller at 1.52 μm, and the absolute value of the potential increased to 19.9 mV when the mass ratio of SPI to DS was 1:1 and the pH was 3.5. With the DS ratio increased, the solubility of the composite particles increased to 14.44 times of the untreated protein at pH 3.5, while the surface hydrophobicity decreased. Electrostatic interactions and hydrogen bonds were the main forces between SPI and DS, and DS was electrostatically adsorbed on the surface of SPI. The emulsion stability significantly enhanced with the increase of complex concentration (38.88 times higher than at 1% concentration), the emulsion average droplet size was the lowest (9.64 μm), and the absolute value of potential was the highest (46.67 mV) when the mass ratio of SPI to DS was 1:1 and the complex concentration of 8%. The stability of the emulsion against freezing was improved.

CONCLUSION

The SPI/DS complex has high solubility and stability under low acidic conditions, and the SPI/DS complex' emulsion has a well stability. This article is protected by copyright. All rights reserved.

Effect of Thermal Pretreatment on the Physiochemical Properties and Stability of Pumpkin Seed Milk

During the production of plant-based milk, thermal treatment of raw materials is an important processing method to improve the physicochemical and nutritional quality of the final products. The objective of this study was to examine the impact of thermal processing on the physiochemical properties and stability of pumpkin seed (Cucurbita pepo L.) milk. Raw pumpkin seeds were roasted at different temperatures (120 °C, 160 °C, and 200 °C), and then processed into milk using a high-pressure homogenizer. The study analyzed the microstructure, viscosity, particle size, physical stability, centrifugal stability, salt concentration, heat treatment, freeze-thaw cycle, and environment stress stability of the resulting pumpkin seed milk (PSM120, PSM160, PSM200). Our results showed that the microstructure of pumpkin seeds was loose and porous, forming a network structure because of roasting. As the roasting temperature increased, the particle size of pumpkin seed milk decreased, with PSM200 showing the smallest at 210.99 nm, while the viscosity and physical stability improved. No stratification was observed for PSM200 within 30 days. The centrifugal precipitation rate decreased, with PSM200 showing the lowest rate at 2.29%. At the same time, roasting enhanced the stability of the pumpkin seed milk in the changes in ion concentration, freeze-thaw, and heating treatment. The results of this study suggested that thermal processing was an important factor in improving the quality of pumpkin seed milk.

Exploring the influence of ultrasound on the antibacterial emulsification stability of lysozyme-oregano essential oil

A lysozyme-oregano essential oil (Lys-OEO) antibacterial emulsion was developed via ultrasonic treatment. Based on the general emulsion materials of ovalbumin (OVA) and inulin (IN), the addition of Lys and OEO successfully inhibited the growth of E. coli and S. aureus, two representatives of which were Gram-negative and Gram-positive bacteria respectively. The emulsion system in this study was designed to compensate for the limitation that Lys could only act on Gram-positive bacteria, and the stability of the emulsion was improved using ultrasonic treatment. The optimal amounts among OVA, Lys and OEO were found to be the mass ratio of 1:1 (Lys to OVA) and 20% (w/w) OEO. The ultrasonic treatment at the power of 200, 400, 600, and 800 W and time length of 10 min improved the stability of emulsion, in which the surface tension was below 6.04 mN/m and the Turbiscan stability index (TSI) did not exceed 10. The multiple light scattering showed that sonicated emulsions were less prone to delamination; salt stability and pH stability of emulsions were improved, CLSM image showed emulsion as oil-in-water type. In the meantime, the particles of the emulsions were found to become smaller and more uniform with ultrasonic treatment. The best dispersion and stability of the emulsion were both achieved at 600 W with a zeta potential of 7.7 mV, the smallest particle size and the most uniform particle distribution.

Improving the physicochemical stability of Pickering emulsion stabilized by glycosylated whey protein isolate/cyanidin-3-glucoside to deliver curcumin

Protein-polysaccharide-polyphenol delivery systems function as a promising tool to deliver bioactive ingredients aiming to improve their solubility and bioavailability. In this study, whey protein isolate (WPI), short-chain inulin (SCI), and cyanidin-3-glucoside (C3G) were first used to stabilize Pickering emulsions. The physicochemical properties and stability of curcumin encapsulated or not in Pickering emulsions were explored. Results showed that glycosylation and C3G reduced surface and interfacial tension on protein surfaces and inhibited the aggregation of emulsion droplets, thereby reducing the emulsion's particle size. WPI-SCI/C3G stabilized Pickering emulsion had the best stability. The CLSM results showed that the WPI-SCI and WPI-SCI/C3G stabilized emulsions were uniformly dispersed, suggesting that glycosylation and the interaction between protein and C3G enhanced the adsorption capacity of the interfacial protein and improved the stability of the Pickering emulsion. The retention rates of curcumin-loaded WPI-SCI- (67.34 %) and WPI-SCI/C3G- (77.07 %) stabilized Pickering emulsions on day 8 of storage were higher than those in WPI- (33.97 %) and WPI/C3G- (37.02 %) stabilized emulsions, and the degradation half-life was also extended from 7 days to >15 days. These findings provide a theoretical basis for the application of WPI Pickering emulsion and indicate a useful means for the delivery of bioactive components.

A combined approach for modifying pea protein isolate to greatly improve its solubility and emulsifying stability

Pea protein-based delivery systems have drawn much attention in the food and pharmaceutical fields in recent years. However, its broad application faces great limitations because of the low solubility. Here, we present a novel and effective approach to overcome this difficulty and enhance the techno-functional characteristics, especially emulsifying stability, of the pea protein isolate (PPI). By combining pH-shifting with ultrasound and heating (PUH), we concluded that the solubility of PPI greatly increased from 29.5 % to 90.4 %, whereas its surface hydrophobicity increased from 1098 to 3706. This was accompanied by the changes of PPI structure, as shown by circular dichroism and scanning electron microscopy. In addition, the modified PPI was applied to stabilize sunflower oil-in-water emulsions. The droplet size of the emulsion with PUHP was reduced and its emulsion stability was significantly elevated. Taken together, we propose a novel combined approach to prepare modified PPI with high solubility and emulsion stability. We expect our method will have a wider application in modifying plant proteins and improving their industrial processing.

Effect of ultrasonic power on the emulsion stability of rice bran protein-chlorogenic acid emulsion

In this study, rice bran protein-chlorogenic acid (RBP-CA) emulsion was subjected to an ultrasonic-assisted treatment technique. The encapsulation efficiency and loading capacity of chlorogenic acid (CA), and the morphology, particle size, zeta (ζ)-potential, atomic force microscopy image, viscosity, turbidity, and interfacial protein content of the emulsion under different ultrasonic power were investigated. The results revealed that the emulsion exhibited an encapsulation efficiency and loading capacity of 86.26 ± 0.11% and 17.25 ± 0.06 g/100 g, respectively, at an ultrasonic power of 400 W. In addition, the size of the emulsion droplets decreased and became more evenly distributed. Furthermore, the viscosity of the emulsion decreased significantly, and it exhibited a turbidity and interfacial protein content of 24,758 and9.34 mg/m², respectively. Next, the storage, oxidation, thermal, and salt ion stabilities of the emulsion were evaluated. The results revealed that the ultrasonic-assisted treatment considerably improved the stability of the emulsion.

Emulsifying and emulsion stabilizing properties of hydrolysates of high-density lipoprotein from egg yolk

High-density lipoprotein (HDL) was extracted from hen eggs and enzymatic hydrolysates were formed by neutral protease, trypsin and alkaline protease, which were named as EHN, EHT and EHA, respectively. The solubility of hydrolysates was significantly higher than that of HDL, especially that of EHA significantly increased from 7.69% to 27.54% when it was hydrolyzed for 1.5 h. The emulsifying properties of EHT, EHA and EHN exhibited an increase trend as a function of hydrolysis time and reached the peak values at 3.5, 1.5 and 3.5 h, respectively. This improvement was attributed to the generation of soluble peptides fragments and the exposure of ionizable residues. At different pH, temperatures and ionic strengths, the stability of emulsions stabilized by hydrolysates was higher than that of HDL, especially for emulsions prepared by EHT. These findings might indicate feasible guidance to broaden the application of HDL and enzymatic hydrolysates in emulsions.

Effect of ultrasonic pretreatment on the emulsification properties of Clanis Bilineata Tingtauica Mell protein

Clanis Bilineata Tingtauica Mell Protein (CBTMP) is a naturally high-quality insect protein resource, while its poor emulsification has limited its application in food industry. In order to change the present situation, in this research, the ultrasonic pretreatment (0 W, 200 W, 400 W, 600 W, and 800 W) method was used to improve the emulsification properties of CBTMP. Results indicated that ultrasound treatment especially at 400 W could significantly change the particle sizes, further increase the content of sulfhydryl group and surface hydrophobicity. The emulsification properties of emulsions were enhanced (from 4.16 ± 1.07 m²/g to 27.62 ± 2.20 m²/g) by sonicated CBTMP solution. Moreover, the physical stability of the emulsions to salt stress and centrifugation treatment was also promoted. Additionally, rheology revealed that a stronger network was formed at 400 W and all samples exhibited frequency-dependent and amplitude-dependent properties. The experiment demonstrated that ultrasound pretreatment was an effective means to improve the emulsification properties of CBTMP and it could provide a promising perspective for the application of CBTMP in food industry.

Enhancement of storage stability of surimi particles stabilized novel pickering emulsions: Effect of different sequential ultrasonic processes

Preparation of highly stable Pickeringemulsions stabilized by food grade particles especially with low concentrations is of concern. In this study, the effects of two-step emulsification procedure with different sequential ultrasonic processes on the storage stability, droplets size, zeta potential, microstructures as well as the rheological behaviors of surimi particles-stabilized Pickeringemulsions with 0.6 oil-water ratio were investigated. The results showed that the surimi particles based-emulsions prepared by the homogenization-ultrasonic (H-U) or ultrasonic-homogenization (U-H) method both possessed excellent physical stability during 14 days storage. Particularly, the stability index of emulsions all exceeded 99.5% in the U-H groups. The confocal laser scanning microscopy (CLSM) and cryo-scanning electron microscope (cryo-SEM) images provide evidence that more particles attached on the oil-water interfaces and the network structures formed via particle-particle interactions obviously arrested phase separation in H-U and U-H emulsions. Moreover, the Pickering emulsions obtained by two-step method all exhibited higher viscosity and storage modulus values, which were also conducive to the special storage stability of samples. In short, the storage stability of protein based-Pickering emulsions can be enhanced using homogenization-ultrasonic (H-U) or ultrasonic-homogenization (U-H) procedure.

Low-intensity ultrasound enhances the antimicrobial activity of neutral peptide TGH2 against Escherichia coli

In recent years, foodborne diseases caused by Escherichia coli are a major threat to the food industry and consumers. Antimicrobial peptides (AMPs) and ultrasound both have good inhibitory effects on E. coli. In this work, the mechanism of action and synergistic effect of an in silico predicted AMP, designated as TGH2 (AEFLREKLGDKCTDRHV), from the C-terminal sequence of Tegillarca granosa hemoglobin, combined with low-intensity ultrasound was explored. The minimal inhibitory concentration (MIC) of TGH2 on E. coli decreased by 4-fold to 31.25 μg/mL under 0.3 W/cm2 ultrasound treatment, while the time kill curve analysis showed that low-intensity ultrasound combined with peptide TGH2 had an enhanced synergistic bactericidal effect after 0.5 h. The permeability on E. coli cell membrane increased progressively during combined treatment with peptide TGH2 and low-intensity ultrasound, resulting in the leakage of intracellular solutes, as shown by transmission electron microscopy (TEM). Structural analysis using circular dichroism (CD) revealed that peptide TGH2 has an α-helical structure, showing a slight untwisting effect under 0.3 W/cm2 ultrasound treatment for 0.5 h. The findings here provide new insight into the potential application of ultrasound and AMPs combination in food preservation.